자동차 대여 기록 별 대여 금액 구하기(Oracle) - programmers

https://school.programmers.co.kr/learn/courses/30/lessons/151141

문제를 잘읽자..!

select history_id, (100-
                   (select discount_rate
                    from(   
                        select nvl(max(discount_rate),0) discount_rate --dates가 7미만일 경우
                        from CAR_RENTAL_COMPANY_DISCOUNT_PLAN 
                        where car_type = '트럭'
                        and REGEXP_REPLACE(DURATION_TYPE, '[^0-9]') <= x.dates --REGEXP_REPLACE 숫자만 빼기
                        order by 1
                        )
                    where rownum = 1)
                   ) * x.dates * x.daily_fee/100 FEE
from (
    select HISTORY_ID, a.car_id, (a.end_date-a.start_date)+1 dates, b.daily_fee --그냥 빼면 0인날이 되므로 하루만썼어도 하루되기위해 +1
     from CAR_RENTAL_COMPANY_RENTAL_HISTORY a, 
            (SELECT car_id,daily_fee
            from CAR_RENTAL_COMPANY_CAR 
            where car_type = '트럭') b
    where a.car_id = b.car_id
    ) x
order by 2 desc, 1 desc